1. Field of the Invention
The present invention relates to a new type of antioxidant containing an organogermanium compound as a principal ingredient.
2. Description of the Prior Art
Oxygen is an indispensable substance not only for human beings but also for all aerobic organisms, but it is well known that oxygen causes various undesired phenomena. For example, fat or oil contained in food is auto-oxidized with oxygen in air to result not only in a decrease in the quality as a favorite food and the nutritive value, but also in the generation of toxic substances by the formation of peroxides. Further, in living organisms, the formation of peroxides is recently noted as a cause of aging, cancerogenesis or the like.
That is to say, it is believed that an unsaturated fatty acid, for example, polyunsaturated fatty acid which is particularly important as phospholipids or the like and is an indispensable component in food as an essential fatty acid, is subjected to auto-oxidation with free radical of oxygen or oxidant, which is a free radical chain reaction, to form peroxylipids called "hydroperoxide", and this hydroperoxide and products formed by the oxidative destruction of endo-peroxide generated during the auto-oxidation, such as malonaldehyde, act on DNA, RNA, protein or membrane tissue, thus taking part in the above diseases.
Adriamycin contained in anthracycline antineoplastic agent which is one of chemotherapeutic agents used in the medical treatment of carcinoma is known to have a particularly wide antineoplastic spectrum. However, it has been reported that adriamycin exhibits some side effects. Furthermore, it has been proposed that cardiotoxicity which is one of the side effects is caused by the peroxidation of lipid with superoxide anion free radical (O.sub.2.sup.-), hydroxyl free radical (OH), singlet oxygen ('O.sub.2) or the like which are derived from the quinone structure present in the chemical structure of adriamycin (Edward G. Mimnaugh et al., the Journal of Pharmacology and Experimental Therapeutics, Vol. 226, No. 3,806 (1983)).
Many efforts have been made to inhibit the above auto-oxidation. Presently, synthesized phenolic antioxidants such as butylhydroxyanisole (BHA) or butylhydroxytoluene (BHT) and natural antioxidants such as tocopherol are known and the former is widely used.
However, these synthetic antioxidants have disadvantages with respect to safety. For example, BHA tends to cause disturbances in a liver. On the contrary, natural antioxidant are known to have disadvantages with respect to the source of supply, effects and cost. Therefore, some of the inventors of the present invention had investigated in order to find effective natural antioxidant other than tocopherol and succeeded in developing an effective, safe and natural antioxidant containing n-tritriacontane-16, 18-dione which is contained in leaf wax of eucalyptus, as a principal ingredient (Japanese Patent Publication No. 57-26744). Further, it is also desired that effective, safe and synthetic antioxidants are developed.